How much would people pay to save the iconic monarch butterfly? A lot, according to a new study in Conservation Letters. Based on survey data, the authors estimate that American households are willing to spend about $4 to 6 billion to support monarch conservation.

Even people who aren’t butterfly-lovers are likely to have heard about the monarchs’ spectacular migrations from the northern U.S. and Canada to Mexico and California. “People’s interest in monarchs and their fascinating, visible biology is obvious,” the researchers write. They note that seven states have adopted the monarch as their official insect or butterfly, and the U.S., Canada, and Mexico hold festivals in the monarch’s honor.

But these beloved butterflies may be in peril. Their winter colonies have shrunk over the last decade, and the number of monarchs in Mexico hit a new low last year. The butterflies’ host plant, milkweed, has been vanishing from U.S. farms. And some studies suggest that climate change could increase the prevalence of parasite infections among monarch populations.

To find out how much people valued the monarch, the study authors analyzed the results of a survey of 2,289 U.S. households. People were asked how much they would pay to plant nectar or milkweed plants for the butterflies at their homes or donate to monarch conservation projects.

Seventy percent of the respondents said that monarch conservation was “important” or “very important,” and only 3 percent deemed it “not important”. Twenty-nine percent said they would be willing to grow nectar plants, and 24 percent were willing to grow milkweed. By extrapolating numbers to the entire country, the authors estimate that Americans would pay $933 million and $473 million for nectar and milkweed plants, respectively.

People also were willing to donate an average of $31 to $41 to help protect monarch habitat. Combined with the plant purchases, that comes out to an estimated total of $4.78 to $6.64 billion in potential monarch-related support across the country.

That’s less than previous valuation estimates for bald eagles, gray whales, and pandas, the team notes. Nevertheless, “[t]he study indicates that economic values of monarch butterflies are potentially large enough to mobilize people for conservation planting and funding habitat conservation,” said study co-author John Loomis of Colorado State University in a press release. — Roberta Kwok | 30 October 2013